Strip chart recorder

ABSTRACT

A strip chart recorder of the pneumatic type is disclosed which has a removably mounted chart magazine assembly and drive therefor with a chart rewinding mechanism which maintains the chart in tension. Amplification of the analog pressure signals is provided by a servo operating a bell crank. The pens and associated indicating pointers are gravity urged toward their zero positions.

United States Patent Packel [s41 STRIP CHART RECORDER [72] Inventor:Morton A. Packel, Philadelphia, Pa.

[73] Assignee: Moore Products Co., Spring House,

22 Filed: Oct. 23, 1976 a 211 Appl.No.: 83,385

[52] US. Cl. ..346/72, 346/139 R, 346/136 [51] Int.Cl. ..G0ld 5/06 3[58] Field of Search ..346/72, 136, 139 R, 145; I

56 References Cited UNITED STATES PATENTS 9/1958 Virbila ..-..346/72X4/1952 DiMaggio ..346/l39X 2,913,299 11/1959 Clift ..346/136 X 3,209,3639/1965 -Virbila ..346/72 X 3,306,548 2/1967 Polder ..346/l36 UX PrimaryExaminer-Joseph W. Hartary Attorney-Zachary T. Wobensmith [57] ABSTRACTA strip chart recorder of the pneumatic type is disclosed which has aremovably mounted chart magazine assembly and drive therefor with achart rewinding mechanism which maintains the chart in tension.Amplification of the analog pressure signals is provided by a servooperating a bell crank. The pens and associated indicating pointers aregravity urged toward their zero positions.

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Arron/var //vv/v 7105 MORTON A. PAC/(EL ATTORNEY P'A'TE'N TEDB 19123.705425 sum '5 OF 5 INVENTOR MORTON A. PAQKEL BY ATTORNEY STRIP CHARTRECORDER BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to a strip chart recorder of the pneumatic type whichis operated by signals from one or more pneumatic transmitter ortransducer type in- SUMMARY OF THE INVENTION In accordance with thisinvention, a strip chart recorder is provided which has an improvedchart magazine assembly and drive thereforwith continuously availablerewind or takeup, the chart magazine assembly being readily movable intoposition for recording, movable to a position for chart replacement andremovable from the recorder chassis, with pneumatic amplification of theanalog pressure signal and application of the amplified signal to thechart by a bell crank for mechanical amplification and change ofdirection, the recorder being readily adaptedfor use in new and inexisting installations. I

It is the principal object of the present invention to provide animproved strip chart recorder which will be free from the shortcomingsof strip chart recorders heretofore available.

It is a further object of the present invention to provide 'a stripchart recorder having animproved drive and rewind mechanism fordetermining the chart movement.

It is a further object of the present invention to provide a strip chartrecorder having an improved recording pen actuating mechanism whichincludes a bell crank operator with gravity return of the pen arm.

It is a further object of the present invention to provide a strip chartrecorderv in which recording is effected on a chart having rectilineartime lines.

It is a further object of the present invention to provide a strip chartrecorder having high calibration accuracy, a high order ofrepeatability, excellent resolution, low hysteresis, low airconsumption, and low supply pressure effect.

Other objects and advantageous features of the invention will beapparent from the description and claims.

. BRIEF DESCRIPTION OF THE DRAWINGS The nature and characteristicfeatures of the invention will be more readily understood from thefollowing description taken in connection with the accompanying drawingsforming part thereof, in which:

FIG. 1 is a top plan view of a strip chart recorder in accordance withthe invention;

F IG. 2 is a side elevational view of the recorder, shown in FIG. 1;

FIG. 3 is a fragmentary horizontal sectional view, enlarged takenapproximately on the line 33 of FIG. 2;

FIG. 4 is an exploded perspective view of the ink cartridge and the penarm connection;

FIG. 5 is a front elevational view showing the chart, the pens and theindicator scales;

' FIG. 6 is an end view as seen from the line 66 of FIG. 7 is anexploded perspective view of the bell crank drive; and

FIG. 8 is a diagrammatic view of a portion of the actuator system.

It should, of course, be understood that the description and drawingsherein are illustrative merely and that various modifications andchanges can be made in the structure disclosed without departing fromthe spirit of the invention.

Like numerals refer to like parts throughout the several views.

pen and DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now moreparticularly to the drawings, the strip chart recorder in accordancewith the present invention preferably includes a base plate 10 on whicha plurality of actuatorassemblies such as the actuator assemblies 11a,11b and He, are mounted.

I Each of the actuator assemblies includes a body portion 14 which issecured to the base plate 10 by screws (not shown).

Each of the actuator assemblies (see FIG. 8) includes a forcebeam 15secured to the body portion 14 by a hinge plate 16 and with a zeroadjusting spring 17 between the body portion 14 and the beam 15. Anadjusting screw 18 is provided to adjust the zero spring 17.

An input bellows 19 is provided between the body portion 14 and theforce beam 15 to which the input signal is supplied through a signalinput connection 20.

A motion lever 25 is provided pivotally carried on an actuator housing26 by a pivot pin 27. The housing 26 is preferably integral with thebody portion 14 and has an actuator chamber 28 therein which is boundedin part by a diaphragm 29 and is connected in operating relation to themotion lever 25 by a rod 30. The rod 30 bears on a ball 31 secured tothe center a diaphragm 29 at a point interior of the chamber 28 withrespect to the flexible portion of the diaphragm 29 to providemechanical stability without guides.

A supply connection 35 is provided to a source 0 fluid under pressure,and preferably pressure regulated and filtered air. The supplyconnection 35 is connected to a fluid passageway 36 extending todiaphragm chamber 28 and having a supply restriction 37 therein and adamping restriction 38 therein. A nozzle 39 connected to the fluidpassageway 36 between the restrictions 37 and 38 is controlled by thepositioning of the force beam 15 with respect thereto.

A feed back spring 40 has one end engaged with the force beam 15 at aselected location 41a, b, c, and to a travelling link 42 carried on avernier span adjustment screw 43 on the motion lever 25.

The motion lever 25 has an end plate portion 44 with an opening 45 forengagement by a ball 46 on a drag link 47.

The drag links 47 for the respective actuator assemblies 11a, 11b and11c are of different lengths, and are each pivotally connected by pivotpins 50 to their respective bell cranks 51. The bell cranks 51 areseparately pivotally mounted in a pin arm bracket 54 by pivot pins 52and have pin arms 55 slidably engaging pen assemblies 56 with circulardiscs 57. The respective lengths of the arms of the bell cranks 51determine the mechanical amplification effected.

The pen assemblies 56 are guided in their vertical movement, as urgedupwardly by the pen arms 55 and downwardly by gravity, by guides 53which are slidable on vertical guide rods 58 of circular cross sectionwhich serve as ways. The guide rods 58 are detachably engaged at theirlower endsin the base plate and at their upper ends are detachablycarried by a frame 59 mounted on the base plate 10. 1

Flexure springs 60 are connected to the assembly 56 and bear against thepen arms 55.

Eachpen assembly 56 includes an ink cartridge 61 with ink therein of thedesired color and an ink tube 62 and pen or stylus 63. The pens 63' arepreferably of fibrous material.

The frame 59 has value scales 64 carried thereon and the ink tubes 62have pointer fingers 65 mounted thereon for cooperation with the scales64.

A detachable chart assembly and driving mechanism therefor is alsoprovided. For this purpose, a chart drive motor 66 is mounted on a motorsupporting bracket 67 on the base plate 10. The drive motor 66 can be ofany desired type but in one embodiment is a 110 volt AC 60 Hz motor todrive the chart C at a standard chart speed of seven-eighths of an inchper hour.

The drive motor 66 has a built in overrunning clutch (not shown) topermit manual chart adjustment in the forward direction and has anoutput shaft 68 carrying a gear 70.

A chart magazine 72 is provided which includes a chart frame 74 which isdetachably and pivotally carried on the base plate 10 with a notch 75engaging a headed pivot pin 76. The chart frame 74 has a chart drivingdrum 77 pivotally mounted thereon with a gear 78 at its lower end fornormal engagement by the gear 70, but capable of being disengaged uponswinging of the chart frame 74 about the pivot pin 76 to a position fordisengagementat the notch 75. A hand wheel 73 is provided for manualrotation of the drum 77, if desired and chart drive pins 79'can be,provided on the drum 77.

The chart frame 74 also has a vertical chart supply spindle 80 thereononto which a roll of strip chart C is supplied, a vertical chart guiderod 81, a vertical chart back up bar 82, a vertical chart back up plate83, and a bushing and guide post 84.

A lower spool guide 85 is pivotally mounted on the frame 74 with freedomto nutate.

At the upper end of the post 84 an upper spool guide 87 is provided withfreedom to nutate and rotate on a pivot carried on a pivotally mountedlocating plate 88. The spool guides 85 and 87 carry a chart collectingspool 89;, keyed to a gear 86 for rotation therewith.

Arewind or chart take up motor 90 is mounted on a bracket 91 on the baseplate 10. The motor 90 can be of any desired type but in one specificembodiment of the invention is a hysteresis synchronous motor suitablefor continuous duty when stalled and can be a l 10 volt 60 AC l-lz motorwith a shaft speed of 100 rpm.

The motor 90 has a motor shaft 94 with a gear 95 secured thereto fornormal continuous engagement with the gear 86 but disengageable uponremoval of the chart frame 74.

A spring urged latch finger 96 on the chart frame 74 normally engages alatch pin 97 on the base plate 10 and releasably retains the chartmagazine in operating position. Release of the latch finger 96 permitsswinging of the chart frame 74 about pivot pin 76 as an axis and slidingmovement at the notch to disengage the chart frame 74 from the pin 76.

A mounting plate 98 supported on posts 99 above the base plate 10, has apneumatic connection block 100 mounted thereon, with fluid connectionsto the supply, and to the input signals, and to the actuator assemblies11a, 11b, and 11c.

The mode of operation will now be pointed out.

Air under pressure is supplied from the supply connection to each of theactuator assemblies. The air is delivered into the fluid connection 36through the restriction 37 and through the restriction 38 to thediaphragm chamber 28 where it is effective against the diaphragm chamber28 where it is effective against the diaphragm 29 for applying a forcethrough the rod 30 against the motion lever 25. The pressure in thefluid connection 36 and in the chamber 28 is determined by thepositioning of the force beam 15 with respect to the nozzle 39 tocontrol the escape of air therethrough.

The force beam 15 is positioned by the pressure applied in the bellows19 through the input connection 20. Adjustment of the spring 17determines the zero position of the beam 15 and the feedback spring 40by its connection to the motion lever 25 is effective for rebalancingthe force beam 15 to its initial position prior to any change effectivethereon.

The positioning of the motion lever 25 positions the drag link 47 andthis link 47 through the bell crank 51 moves the bell crank pen arm 55.The pen assembly 56 is positioned by the disc 57 in engagement therewithto raise or lower the pen arm 55 in accordance with the input signal inthe bellows 19.

The pen arm 55 moves the pen assembly 56 vertically on the appropriateguide rod 58 to position the ink tube 62 and the pen 63 carried therebyon the chart C. At the same time the pointer finger 65 carried by thetube 62 is positioned with respect to its value scale 64.

It will be noted that positive forces are applied to raise the penassemblies 56 but that these are lowered by the action of gravity.

The pens 63 are effective on the chart C to record, with amplification,the signals in the respective input bellows 19.

The chart C carried in the chart magazine 72 is advanced from the rollon the supply spindle by the engagement of the chart drive pins 79 onthe drum 77.

The chart drive motor 66 through the motor shaft 68 and gears 70 and 78rotates the drum 77 for chart advance.

The motor is effective through the shaft 94 and gear which is engagedwith the gear 86 to apply a torque continuously on spool 89 to maintainthe chart C previously attached to the spool 89 under tension.

The chart magazine 72 can be removed by releasing the latch finger 96from engagement with the pin 97 and swinging the magazine 72 to theposition shown in broken lines in FIG. 3. The chart C may then beshifted by turning the hand wheel 73 to turn thedrum' 77 in eitherdirection.

The magazine 72 can then, if desired, be completely removed by slidingat the notch 75 to disengage the pin 76.

Access to the spool 89 is available by raising the locating plate 88 toa position to clear the spool 89 and swinging it to a position forremoval of afilled spool 89 and replacement by an empty spool 89 towhich a new chart C is attached.

Although a three pen recorder has been described one or more of the penscould be omitted while retaining the pointer fingers 65, if desired.

It will thus be seen that a recorder has been provided with which theobjects of the invention are attained.

I claim:

1. A strip chart recorder for recording a condition representing ananalog pressure comprising an output member connected to said take offconnection and said recording means, and a resilient feed backconnection between said output member and said valve means.

* it t a

1. A strip chart recorder for recording a condition representing ananalog pressure comprising recording means, analog pressure sensingmeans, valve means controlled by said sensing means and supplyingcontrolled fluid pressure from a source, motor means controlled by saidvalve means comprising a diaphragm chamber within which the pressurefrom said valve means is effective, a flexible diaphragm member boundingsaid diaphragm chamber, a pivotal take off connection inset within thediaphragm chamber with respect to said diaphragm member, and an outputmember connected to said take off connection and said recording means,and a resilient feed back connection between said output member and saidvalve means.